Engine starter gearing



Dec. 20, 1955 J. E. BUXTON 2,727,998

ENGINE STARTER GEARING Filed June 23, 1954 2 Sheets-Sheet l WI TNESS.

TOBNEY Dec. 20, 1955 J. E. BUXTON 2, ,998

ENGINE STARTER GEARING Filed June 23, 1954 2 Sheets-Sheet 2 IN V EN TOR. Jwnes 6. fiMEn RNEY WITNESS.

2,727,998 ENGINE STARTER GEARING James E. Buxton, Elmira, N. Y., assignor to Bendix Aviation Corporation, Elmira Heights, N. Y., a corporation of Delaware Application June 23, 1954, Serial No. 438,663 Claims. (Cl. 290-38) The present invention relates to engine starting gearing and more particularly to that type in which a motor driven pinion is shifted into and out of mesh with an the engine and the starting motor have simultaneously exceeded a predetermined speed of rotation.

It is another object to provide such a device which is eflicient and reliable in operation and simple and economical in construction and assembly.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing in which:

Fig. 1 is a side elevation, partly broken away and in section, of a preferred embodiment of the invention showing the parts in idle position; and

Fig. 2 is a similar view showing the parts in cranking position.

In Fig. l of the drawing there is illustrated a starting motor 1 comprising a stationary field 2 and a rotatable armature 3 having a shaft 4 which is mounted for rotary and limited longitudinal movement in hearings in the ends of the motor 1, one of which is shown at 5. The armature shaft 4 is extended outward beyond the bearing 5, and its outer end supported in an outboard hearing 6 attached to the motor frame as indicated at 7.

A pinion 8 is slidably journaled on the armature shaft 4 for movement into and out of mesh with an engine gear 9, and means for actuating the pinion from the armature shaft is provided comprising a hollow sleeve 11 fixed as indicated at 12 to the armature shaft and having an anchor plate 13 non-rotatably mounted thereon and connected by a drive spring 14 to a similar anchor plate 15 non-rotatably fixed on a driving overrunning clutch member 16 which is slidably journaled on the sleeve 11.

to compress the drive spring 28 and thrust washer 29 on Movement of the screw gear 9 is limited by a stop 14 is limited by a shoulder the sleeve 11.

shaft 17 toward the engine ring 31 fixedly mounted on 2,727,998 Patented Dec. 20, 1955 A spring washer 33 and thrust ring 34 are interposed between the end of the screw shaft 17 and the stop ring 31 in order to yieldingly urge the screw shaft into clutching engagement with the clutch member 16.

Means for limiting the demeshing movement of the control nut 21 is provided in the form of shoulders 35 tron relative to the field 2 of the motor by means of a spring 37 which bears at one end against the motor hearing 5, and at its other end against the bottom of a cup member 38 fixed on the armature shaft 4. Expansion annular groove 41, tent 42 is mounted for radial movement in the cup member 38 in position to enter the groove 41 when the armature is in centered position. A spring 43 is arranged to press the detent 42 into the centrifugal force when the armature rotates above a predetermined speed. The detent 42, and the end of the motor bearing 5 are suitably beveled as indicated to permit the detent to slide into the groove 41 when the armature is drawn toward its centered position by initial actuation of the starting motor.

In operation, starting with the parts in the positions as the spring 14 until the backward movement of the clutch member 16 is arrested by the shoulder 28 on the sleeve 11. Thereafter torque is yieldably transmitted through the drive spring 14 to crank the engine.

not continue to be self-operative, cranking will be resumed as soon as the engine speed falls below the corresponding speed of the starting motor.

When a successful start of the engine has been secured, the release of the load on the starting motor permits it to accelerate sufficiently to cause the detent 42 to be withdrawn by centrifugal force from the groove 41. The spring 37 thereupon becomes operative to move the armature back toward its decentered position, which is permitted due to the fact that the high speed of rotation of the idly rotating motor increases the counter electro-motiv'e-forc'e of the motor to a point where the centering attraction of the field for the armature is great- 1y reduced. Deenergizing of the starting motor thereafter permits the parts to return to idle position.

Although but one form of the invention has been shown and described in detail it will be understood that changes may be made in the precise form and arrangement of the parts without departing from the spirit of the invention.

I claim:

1. In an engine starter a motor having a stationary field and a rotatable armature which is shiftable longitudinally into and out of centered position with respect to the field, an armature shaft, a pinion slidably and rotatably mounted thereon for movement thereon and therewith into and out of mesh with a gear of an engine to be started, means for actuating the pinion from the armature shaft including a screw shaft rotatably and slidably mounted on the armature shaft, a control nut threaded thereon rigidly connected to the pinion, an overrunning clutch connection from the armature shaft to the screw shaft, yielding means urging the armature shaft toward its decentered position, and means including a mounting member fixed on the armature shaft and a centrifugal detent carried thereby for resisting decentering movement of the armature shaft below a predetermined speed.

2'. An engine starter as set forth in claim 1 in which the overrunning clutch connection to the screw shaft includes a driving dental clutch member, yielding driving means for actuating the clutch member from the armature shaft, and means responsive to the screw-jack action of the screw-shaft and control nut for compressing the overrunning clutch.

3. An engine starter as set forth in claim 2 including further a stop ring fixed on the armature shaft defining the operative position of the control nut, and an abutment on the armature shaft limiting the movement of the driving clutch member away from the control nut during the cranking operation.

4. An engine starter asset forth in claim 3 including further abutment means fixedly mounted on the armature shaft limiting movement of the driving clutch member toward the screw shaft, and a spring between the screw shaft and said stop ring urging the screw shaft into clutching engagement with the driving clutch member.

5. An engine starter as set forth in claim 1 in which the means for resisting decentering movement of the armature shaft comprises a bearing member fixed to the frame of the starting motor having a boss in telescopic relation with said mounting member, and having a circumferential groove, and said centrifugal detent is arranged to register with said groove when the armature is in centered relation to the motor field.

References Cited in the tile of this patent UNITED STATES PATENTS 1,235,163 Rushmore July 31, 1917 a... min "tw 

